The present invention relates to a high pressure valve for hydrogen gas and a decompression device for hydrogen gas. More particularly, the present invention pertains to a high pressure valve for hydrogen gas and a decompression device for hydrogen gas that are suitable for use in a high-pressure hydrogen gas tank for automobiles driven by a fuel cell.
In the prior art, a high-pressure hydrogen gas tank for an automobile driven by a fuel cell is filled with hydrogen gas at a pressure of 35 MPa. As for a high pressure valve for hydrogen gas attached to the high-pressure hydrogen gas tank, for example, an electromagnetic valve or a pressure reducing valve is used. The pressure reducing valve reduces the pressure of high-pressure hydrogen gas discharged from the electromagnetic valve to a particular pressure (e.g. 1 MPa). As for the electromagnetic valve, a semi-pilot type valve is known in the art. The semi-pilot type valve is switched between an open state and a closed state in accordance with the excitation or de-excitation of a solenoid. In the open state, a pilot valve is separated from a pilot valve seat. In the closed state, the pilot valve contacts the pilot valve seat. When the pilot valve opens, a main valve body separates from a main valve seat to open the valve.
The pressure reducing valve typically includes a valve hole connected to a pressure reducing chamber, which is defined between a body and a diaphragm. Such a pressure reducing valve includes a valve body, which selectively contacts a valve seat located around the valve hole. A valve shaft is connected to the center of the diaphragm. The valve body and the valve shaft are coaxially secured to each other.
Material for the pilot valve and the pilot valve seat in the electromagnetic valve and material for the valve body and the valve seat in the pressure reducing valve are selected as required without any design limitation. In this case also, the pilot valve, the pilot valve seat, the valve body, and the valve seat can withstand a high pressure of 35 MPa and maintains the sealing effectiveness even when the valves are closed.
However, the high-pressure hydrogen gas tank for an automobile driven by a fuel cell in these days is aimed to be filled with hydrogen gas at a higher pressure such as a pressure of 70 MPa. Therefore, if the prior art electromagnetic valve and the pressure reducing valve are actually used in the tank for hydrogen gas having higher pressure, sufficient sealing effectiveness cannot be maintained.